U.S. patent application number 11/167650 was filed with the patent office on 2006-03-23 for absorptive coating on a disc to create a reflective modulation for encryption.
This patent application is currently assigned to Spectra Systems Corp.. Invention is credited to Nabil M. Lawandy.
Application Number | 20060064594 11/167650 |
Document ID | / |
Family ID | 37595999 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060064594 |
Kind Code |
A1 |
Lawandy; Nabil M. |
March 23, 2006 |
Absorptive coating on a disc to create a reflective modulation for
encryption
Abstract
Described herein are systems and methods for digital data
encryption, and more specifically, systems and methods for
providing encryption keys for reading encrypted data. Optical
media, particularly digital disks, are described where a laser
reader accesses digital data on a disk. The disks are coated with a
coating containing an encryption key to access encrypted data in
the digital disk.
Inventors: |
Lawandy; Nabil M.;
(Saunderstown, RI) |
Correspondence
Address: |
KIRKPATRICK & LOCKHART NICHOLSON GRAHAM LLP;(FORMERLY KIRKPATRICK &
LOCKHART LLP)
75 STATE STREET
BOSTON
MA
02109-1808
US
|
Assignee: |
Spectra Systems Corp.
Providence
RI
|
Family ID: |
37595999 |
Appl. No.: |
11/167650 |
Filed: |
June 27, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10665837 |
Sep 18, 2003 |
|
|
|
11167650 |
Jun 27, 2005 |
|
|
|
10702530 |
Nov 5, 2003 |
|
|
|
11167650 |
Jun 27, 2005 |
|
|
|
10165273 |
Jun 6, 2002 |
|
|
|
10702530 |
Nov 5, 2003 |
|
|
|
60296308 |
Jun 6, 2001 |
|
|
|
60310914 |
Aug 8, 2001 |
|
|
|
60311160 |
Aug 9, 2001 |
|
|
|
60435647 |
Dec 20, 2002 |
|
|
|
60412153 |
Sep 18, 2002 |
|
|
|
60489945 |
Jul 22, 2003 |
|
|
|
Current U.S.
Class: |
713/176 ;
G9B/20.002; G9B/7.171 |
Current CPC
Class: |
G11B 7/24056 20130101;
H04L 9/0894 20130101; H04K 1/00 20130101; H04L 2209/60 20130101;
G11B 7/24097 20130101; G11B 20/00086 20130101; G11B 7/0053
20130101; G11B 7/26 20130101; G11B 20/00608 20130101; G11B
2007/24624 20130101; G11B 7/00736 20130101; G11B 7/252 20130101;
G11B 20/00253 20130101; G11B 23/284 20130101 |
Class at
Publication: |
713/176 |
International
Class: |
H04L 9/00 20060101
H04L009/00 |
Claims
1. An information storage disk system comprising: A readable disk
including encrypted data; and A layer coating a surface of said
readable disk, said layer comprising a readable pattern; said
readable reflective pattern including an encryption key to access
said encrypted data.
2. The information storage disk system of claim 1 wherein said
layer comprises a cured polymer resin system.
3. The information storage disk system of claim 2 wherein said
cured polymer resin system comprises a photoinitator, an acid
catalyst, and a reactive polymeric unit.
4. The information storage disk system of claim 3 wherein said
reactive polymeric unit comprises an acrylic group.
5. The information storage disk system of claim 3 wherein said
cured polymer resin further comprises a second photoinitiator, and
wherein said photoinitiaor and said second photoinitiator are
activated by different wavelengths of radiation.
6. The information storage disk system of claim 5 wherein said
second photoinitiator initiates optical changes to said layer
coating upon activation by a preselected wavelength of
radiation.
7. The information storage disk system of claim 1 wherein said
readable pattern is selected from the group of concentric rings and
radial lines.
8. The information storage disk system of claim 1 wherein said
readable pattern is varied in response to a radial distance of said
readable pattern on said readable disk.
9. The information storage disk system of claim 1 wherein said
encryption key is varied in response to a radial distance of said
encryption key on said readable disk.
10. The information storage disk system of claim 9 wherein said
encrypted data is encrypted using an encryption key in response to
a radial location of said encrypted data on said disk.
11. The information storage disk system of claim 1 wherein said
information storage disk system comprises one of a compact audio
disc, and a digital versatile disk.
12. A method of making an information storage disk system
comprising: Recording encrypted data on a readable disk; and
Coating said disk with a polymeric coating including a readable
pattern, said pattern including an encryption key to access said
encrypted data.
13. The method of claim 12 wherein said polymeric coating is formed
by the method comprsing: Spin coating a flowable polymer
composition on said readable disk; Masking said polymer composition
with a mold including a pattern; and Curing said flowable polymer
composition with actinic radiation.
14. The method of claim 13 wherein curing said flowable polymer
composition comprises an acid-catalyzed curing reaction.
15. The method of claim 12 wherein said polymeric coating comprises
a photoinitator, an acid catalyst, and a reactive polymeric
unit.
16. The method of claim 15 wherein said reactive polymeric unit
comprises an acrylic group.
17. The method of claim 13 further comprising initating optical
changes in said polymeric coating by activating second
photoinitiators with actinic radiation.
18. The method of claim 12 wherein said readable reflective pattern
is selected from the group of concentric rings and radial
lines.
19. The method of claim 12 wherein said readable reflective pattern
is varied in response to a radial distance of said readable
reflective pattern on said readable disk.
20. The method of claim 12 wherein said encryption key is varied in
response to a radial distance of said encryption key on said
readable disk.
21. The method of claim 20 wherein said encrypted data is encrypted
using an encryption key in response to a radial location of said
encrypted data on said disk.
22. A method of accessing information from an information storage
disk system comprising: Providing a readable disk with a polymeric
coating, said readable disk including encrypted data, said
polymeric coating including a readable pattern; said pattern
including an encryption key to access said data; Obtaining said
encryption key in response to said pattern; Reading said encrypted
data; and Decrypting said encrypted data with said encryption
key.
23. The method of claim 22 wherein obtaining said encryption key
comprises scanning said reflective readable pattern using a first
wavelength of light and wherein reading said encrypted data
comprises scanning said encrypted data with a second wavelength of
light.
24. The method of claim 22 wherein said information storage disk
system comprises one of a compact audio disc, and a digital
versatile disk.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is filed under 35 U.S.C. .sctn.120
as a Continuation-In-Part of and claiming priority to co-pending
U.S. patent application Ser. Nos. 10/665,837, filed Sep. 18, 2003,
and Ser. No. 10/702,530, filed Nov. 5, 2003; which in turn claim
priority to co-pending U.S. patent application Ser. No. 10/165,273
filed Jun. 6, 2002; which in turn claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Application Ser. No. 60/296,308
filed Jun. 6, 2001, U.S. Provisional Application Ser. No.
60/310,914 filed Aug. 8, 2001, and U.S. Provisional Application
Ser. No. 60/311,160 filed Aug. 9, 2001; this patent application
further claiming priority under 35 U.S.C. .sctn.119(e) to U.S.
Provisional Application Ser. No. 60/412,153 filed Sep. 18, 2002;
and U.S. Provisional Application Ser. No. 60/489,945 filed Jul. 22,
2003. The disclosures of all of these applications are incorporated
by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates generally to systems and
methods for digital data encryption, and more specifically, to
systems and methods for providing encryption keys for reading
encrypted data.
BACKGROUND OF THE INVENTION
[0003] The emergence of digital technology, including audio and
video recordings on digital disks which are optically read, has
provided consumers with high quality audio and video entertainment.
The improved format, while providing higher quality, also poses new
threats to copyright owners through the unauthorized reproductions
of digital disks. Through simple means typically available to
anyone with a personal computer, consumers can easily make high
quality unauthorized copies of copyrighted data in digital
disks.
[0004] In order to prevent unauthorized reproduction of disks
containing digital data, producers of digital disks encode digital
data on the disk, and also provide an encryption key to access the
data on the disk. Typically, a serial number or identification
number is provided in machine-readable form to provide an access
code for encryption. Encryption keys are well-known and prevent
widespread reproduction of copyrighted material. With their
increased use however, methods of cracking encryption keys to
access the data have also been developed.
[0005] Another approach to protect copyrighted content is to embed
a watermark into multimedia content such as audio and video,
wherein these watermarks are imperceptible to the human eye.
Detectors can be deployed in hardware or software to meet real-time
play and record control requirements in a wide range of platforms
like dvd. With an efficient detector implementation and robust
watermark encoding, the watermark can survive a wide variety of
professional and consumer analog-to-digital and digital-to-analog
transformations and video processing.
[0006] Still another security technique involves the use of secure
data types. Secure data types are enhanced protected integers that
generate a secure environment less susceptible to protected
function or emulation blackbox attacks. Secure data types compile
into complex code, adding significant difficulty to formulas. The
more secure data types that are implemented into the code, the
greater the effort required to strip away the security of each
secure data type.
[0007] These security systems nonetheless, suffer from natural
limitations associated with the technology. Secure data types are
limited in that security increases proportionally with the
complexity and number of secure data types in the code, and as the
complexity and number increase, so does its cost. Similarly, a
conventional watermark detector must comprise some kind of memory,
and the complexity of the watermark detectors is increasingly
dominated by the RAM necessary to do its computations. This also
leads to increased costs associated with the security system.
[0008] Additional problems, such as those associated with integrity
and confidentiality, are also observed when watermark detectors
share memory resources. The integrity problem involves that
external RAM is reasonably easy to access, and a hacker wanting to
obstruct the watermark detection function could replace the data
stored by the detector through zeroes or dummy data before it is
retrieved again by that detector. The confidentiality problem is
illustrated by the fact that a hacker could glean information about
the precise shape of the watermark by studying the data stored in
the external memory.
[0009] There is a need therefore for a more efficient encryption
system which is not cost-prohibitive, yet provides adequate
safeguards against unauthorized reproduction.
SUMMARY OF THE INVENTION
[0010] Provided herein is an information storage disk system. The
information storage disk system is comprised of a readable disk
including encrypted data, and a layer coating a surface of the
readable disk. The layer includes a readable reflective pattern,
and the readable pattern includes an encryption key to access the
encrypted data.
[0011] In a non-limiting embodiment, the layer coating of the
information storage disk system includes a cured polymer resin
system. In another non-limiting embodiment, the polymer resin
system includes a photoinitator, an acid catalyst, and a reactive
polymeric unit. The reactive polymeric unit may be selected from a
variety of acrylic groups.
[0012] In another non-limiting embodiment, the readable pattern is
selected from the any image, text, or other graphical
representation in the coating. The readable reflective pattern is
therefore varied in response to a radial distance of the readable
reflective pattern on the readable disk. In a non-limiting
embodiment, the readable pattern may be concentric rings, radial
lines, or any pattern capable of including an encryption key
therein. The encryption key may also be varied in response to a
radial distance of the encryption key on said readable disk. The
encrypted data may also be encrypted using an encryption key in
response to a radial location of the encrypted data on the readable
disk. The information storage disk system may be one of a compact
audio disc, and a digital versatile disk.
[0013] Provided also herein is a method of making an information
storage disk system. The method is comprised of recording encrypted
data on a readable disk, and then coating said disk with a
polymeric coating including a readable pattern, the pattern
including an encryption key to access the encrypted data.
[0014] In a non-limiting embodiment, the polymeric coating is
formed by the method of: 1) spin coating a flowable polymer
composition onto the readable disk, 2) masking the polymer
composition with an optical mask, the mask including a pattern, and
3) curing the flowable polymer composition with actinic radiation
passing through the mask. In an embodiment, the flowable polymer
composition is cured by an acid-catalyzed curing reaction.
[0015] Provided also herein is a method of accessing information
from an information storage disk system. The method comprises
providing a readable disk with a polymeric coating. The readable
disk includes encrypted data, and the polymeric coating includes a
readable pattern. The pattern includes an encryption key to access
the data. An encryption key is obtained in response to the readable
pattern, The encrypted data is read then decrypted with the
encryption key.
[0016] In a non-limiting embodiment, the method of obtaining the
encryption key includes scanning the readable pattern using a first
wavelength of light. Reading the encrypted data includes scanning
the encrypted data with a second wavelength of light.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0017] A fuller understanding of the advantages, nature, and
objects of the invention may be had by reference to the following
illustrative description, when taken in conjunction with the
accompanying drawings. The drawings are not necessarily drawn to
scale, and like reference numerals refer to the same items
throughout the different views.
[0018] FIG. 1 is a cross-sectional diagram of a prior art digital
disk.
[0019] FIG. 2 is a cross-sectional diagram of a digital media
having a coating layer in accordance with the teachings herein.
[0020] FIG. 3 shows aspects of the digital reading and decryption
system in accordance with the teachings herein.
[0021] FIG. 4 shows a pattern containing an encryption key in
accordance with the teachings herein.
[0022] FIG. 5 shows a pattern containing an encryption key in
accordance with the teachings herein.
[0023] FIG. 6 shows a pattern containing an encryption key in
accordance with the teachings herein.
DETAILED DESCRIPTION
[0024] Described herein are embodiments of an information storage
disk system. The information storage disk system may be an
optically read digital disk, such as an audio CD, or a DVD. The
storage disk system includes a readable disk including encrypted
data, and a layer coating a surface of said readable disk, the
layer including a readable pattern. The readable pattern includes
an encryption key to access the encrypted data.
[0025] The coating, as disclosed herein, is suited for
incorporation into various components of optical media. It is
recognized that a variety of optical media exist, and that many
have a structure that differs, at least partially, from other
optical media. Therefore, this disclosure teaches what are to be
considered non-limiting embodiments of incorporating a coating into
an optical media. That is, this disclosure does not provide an
exhaustive disclosure of incorporation of the coating into optical
media.
[0026] FIG. 1 discloses aspects of an exemplary optical media known
in the prior art. The optical media 8 includes various layers,
which may be referred to herein as "components" of the optical
media 8. The substrate layer 16 is molded with pits 5 and lands 6
(data features), and is typically formed of polycarbonate or
similar transmissive plastic material. A reflective layer 14 is
deposited on the data features to enable readout by reflection of
an interrogating laser beam. A protective layer 12 is one component
that is typically included to ensure the integrity of the
reflective layer 14 and is typically formed of a UV curable
acrylate coating or similar material. The disc is read through the
substrate layer 16, as indicated by the directional arrow in FIG.
1. Typically, printing or other indicia are placed over the
protective layer 12.
[0027] FIG. 2 provides an illustration of the cross section of an
optical media 10 with a first and introductory embodiment of a
coating 100 applied thereon. In this illustration, the information
storage disk system 10 includes a reflecting layer 14 and a
substrate layer 16. In typical embodiments, the substrate layer 16
is formed of polycarbonate, while the reflecting layer 14 is
metallized (has a reflective metal applied thereon). It is
recognized that aspects of the reflecting layer 14 and a substrate
layer 16 are typically dictated by the specifications for the disk
sytem 10, and therefore are generally not discussed further herein.
The discs 10 typically contain pits 5 and lands 6 as data features.
As disclosed herein, preferably, the coating 100 is applied over
the substrate 16 of the optical media 8. In some embodiments,
aspects of the substrate layer 16 may be adjusted to account for
subsequent preparation of the coating 100. For example, the
substrate layer 16 may be installed with a reduced thickness as
determined by reference to a manufacturer's specification for the
type of optical media 8. Subsequent installation of the coating 100
is then used to increase the thickness of the optical media 10 to
meet the desired thickness specification.
[0028] Optical reading of digital data on disks is well known in
the art. A compact disk or dvd containing data is scanned by a
laser reader which reads data which has been stored on the disk
surface. A detector attached to the laser reader transfers the data
to a data buffer. The data is then decrypted by a decryptor, and
the decrypted data is read, thus playing the audio or visual
data.
[0029] FIG. 3 shows a digital disk reader employing the method of
the present invention. Disk 10 is scanned by a first laser beam 20
from an optical transmitter 19, and the encrypted data in pits 5
and lands 6 reflects the beam 20. The reflected light 21 is then
received by an optical transceiver 23, and relayed to a first
detector 22. From first detector 22, the information is
communicated to first data buffer 26, which is in electronic
communication with first detector 22. Finally, the information is
transferred to decryptor 40, which is in electronic communication
With first data buffer 26.
[0030] Similarly, second laser beam 30 emanates from optical
transmitter 29, and scans disk system 10, reading a readable
pattern 34 on coating 100. Readable pattern 34 selectively reflects
laser 30, and reflected light 31 is received by optical transceiver
33. Pattern 34 contains an encryption key to access data contained
in pits 5 and lands 6. The information, or data, is then relayed to
second detector 32. From second detector 32, the information is
communicated to second data buffer 36, which is in electronic
communication with second detector 32. Finally, the information is
transferred to decryptor 40, which is in electronic communication
with second data buffer 36.
[0031] In one embodiment, first laser 20 and second laser 30 scan
in synchronization with each other, and each follows the same track
so that they are radially positioned at a substantially preselected
spot on the disk at the same time. The dual first and second data
streams are used by the decryptor to decrypt using the encryption
code.
[0032] The laser beams 20 and 30 are of different wavelengths.
First laser beam 20 has a wavelength selected to pass through
pattern 34 on coating 100 substantially without attenuation. Second
laser 30 is selected to be reflected by coating 100. The detectors
22 and 32 are designed to detect light from their respective lasers
20 and 30.
[0033] Many patterns are contemplated for pattern 34 containing the
encryption key. The patterns are chromatically variable by color,
opacity, shade, shape, and a variety of different variables. FIGS.
4-6 show some contemplated patterns. FIG. 4 shows a series of
radially increasing rings 50 positioned on a surface of disk system
10. FIG. 5 shows radial lines 60 emanating from a center 62 of disk
system 10. FIG. 6 shows a pattern 70 similar to a sine curve, in
which the amplitude of the curve increases with its radial distance
from a center 72 of the disk. Additional patterns are contemplated,
including images, text, and other graphical representations in
which the radial response of the readout laser can be varied in a
controlled fashion.
[0034] Coating 100 contains color forming materials necessary for
generation of a color image. The color forming materials may be
configured in a variety of ways, to be discussed further herein.
The color forming materials may be used to develop a gray scale,
single color, or multi-color marking. The coating 100 does not
interfere, or substantially interfere, with the readout of the
optical media 10. That is, the coating 100 and any markings
recorded in the coating 100, do not appreciably absorb or scatter
light at the readout wavelength of the optical media readout laser.
Likewise, the thickness and other aspects of the coating 100 do not
substantially interfere with the readout mechanism.
[0035] In one embodiment, readable pattern 34 may also be varied
with its radial distance on disk 10. The changing pattern 34 with
increased radius corresponds to the encrypted data at a
corresponding point of disk 10.
[0036] The coating 100 contains what can be referred to as two
"sets" of photosensitive materials. One set of photosensitive
materials provides for curing of the coating 100 once the coating
100 is in place. That is, exposure to one set of wavelengths
provides for curing of the first set of photosensitive materials. A
second set of photosensitive materials in the coating 100 exhibits
optical changes upon adequate exposure to a separate set of
wavelengths. Thus, the coating 100 may contain photoinitiators to
initiate crosslinking. The coating 100 may include, but is not
limited to, compounds such as photoacid or photobase generators,
acid or base sensitive dyes, leucodyes, metal chelates, fluorescent
dyes, or laser dyes. The coating 100 may be colored or colorless to
the eye, and may be fluorescent under certain electromagnetic
radiation. Fluorescent emission wavelengths may include, but are
not limited to, a wavelength in the visible region.
[0037] Commonly used readout light wavelengths for the optical
media 10 include 408 nm, 440 nm, 630 nm, 650 nm, and 780 nm, while
other readout wavelengths are possible.
[0038] Although disclosed herein in terms of photosensitive
materials responsive to wavelengths of ultraviolet light (UV), the
coating 100 may include materials that are photosensitive to any
band of wavelengths (also referred to as a "set of wavelengths").
For example, the photosensitive materials may be responsive to
UV-A, UV-B, UV-C, VIS (visible wavelengths), short wavelength
infrared (IR), IR, or long wavelength IR. As one may surmise,
having two sets of photosensitive materials provides for use of two
sets wavelengths to initiate the changes in the coating 100 as
described herein. It is considered that other formulations, not
discussed herein, may advantageously make use of wavelength
separation over the spectrum of useful wavelengths. Accordingly,
the teachings herein are not limited to the exemplary embodiments
herein, which merely provide one example of a system for applying
markings to optical media.
[0039] "Optical media" are referred to herein in general terms,
such as "CD" or "DVD." However, it is considered that optical media
8 encompass many different media formats. For example, the many
formats of optical media 8 include: DVD 5, DVD 9, DVD 10, DVD 14,
DVD 18, DVD-R, DVD-RW, CD-Audio, CD-Video, CD-R, CD-RW, CD-ROM,
CD-ROM/XA, CD-i, CD-Extra, CD-Photo, Super-Audio CD, Mini-Disc a
hybrid format, which may include any-one or more of the foregoing,
Blu-Ray, and others. It is recognized that this is not an
exhaustive list, and should therefore only be considered
illustrative of the variety of optical media formats that may
benefit from the use of this invention.
[0040] Aspects of the development of the coating materials are now
presented. Some embodiments disclosed herein are results of
experimentation. One skilled in the art will recognize that some
embodiments provide certain advantages in certain settings over
other embodiments. Further embodiments may also be developed.
Therefore, it should be recognized that the formulations and the
processes for making and applying a coating are illustrative and
not limiting of the invention herein.
[0041] Early attempts to make a photosensitive color forming
lacquer originated with a combination of acrylates, a
photoinitiator, a photoacid generator (PAG), and a color former.
One of the first formulations that was considered to show desired
properties was composed of about 3% of a photoacid generator (PAG),
about 3% of a color former, and about 94% of a mixture, referred to
as a "coating base." The coating base was formed of a mixture that
included an acrylate and a photoinitiator. Presently preferred
embodiments of the coating base are generally a mixture of
acrylated monomers and oligomers, wetting agents, and a
photoinitiator. The color former and the photoacid generator,
referred to as the "imaging components" are added to the coating
base.
[0042] Initial experimentation with the development of suitable
coating base materials involved an acrylate combination where
SR-494 and SR-238 were mixed in about equal quantities. A
photoinitiator, ESACURE KTO-46, was added to the acrylate
combination so as to be about 10% of the first coating base.
[0043] The chemical equivalents of these materials being: SR-494 is
an ethoxylated (4) pentaerythritol tetraacrylate; SR-238 is a 1,6
hexanediol diacrylate having a low viscosity, fast curing monomer
with low volatility, a hydrophobic backbone, and good solvency for
use in free radical polymerization; and, ESACURE KTO-46 is a stable
liquid mixture of trimethylbenzoyidiphenylphosphine oxide,
.alpha.-hydroxyketones, and benzophenone derivatives. ESACURE
KTO-46 is a liquid photoinitiator that can be incorporated by
simply stirring into a resin system, and is insoluble in water and
is soluble in most common organic solvents and monomers. KTO-46 may
also be referred to as including ESACURE KIP-150 and ESACURE TZT.
The equivalent of ESACURE KIP-150 being an: oligo
[2-hydroxy-2-methyl-1-[4-(1-methylvinyl) phenyl] propanone]; and
ESACURE TZT being an eutectic liquid mixture of: 2,4,6
trimethylbenzophenone and 4 methylbenzophenone.
[0044] ESACURE KTO-46, ESACURE KIP-150 and ESACURE TZT are produced
by Lamberti Spa, Gallarate-Va, Italy. SR-494 and SR-238 are
products of Sartomer Corporation of Exton, Pa. KTO-46 is also
marketed by Sartomer Corporation as SARCURE-1135 (therefore, KTO-46
and SR-1135 are used interchangeably herein).
[0045] Experiments further revealed that applying the coating 100
to an optical media 10 could be achieved by various techniques.
Preferably, the coating 100 is applied by spin coating. However,
during initial applications of the coating 100 by use of spin
coating, the edges of the optical media 10 occasionally exhibited
coverage that was less than desired. It was determined that this
was due to the high surface tension of the lacquer (coating base).
Therefore, wetting agents were added to the coating base to improve
substrate wetting and lower the surface tension were.
[0046] Multiple variations and modifications are possible in the
embodiments of the invention described here. Although certain
illustrative embodiments of the invention have been shown and
described here, a wide range of modifications, changes, and
substitutions is contemplated in the foregoing disclosure. In some
instances, some features of the present invention may be employed
without a corresponding use of the other features. Accordingly, it
is appropriate that the foregoing description be construed broadly
and understood as being given by way of illustration and example
only, the spirit and scope of the invention being limited only by
the appended claims.
* * * * *